1. Field of the Invention
The invention concerns the temporary attachment of an object to a support, the quick release of the object and then its controlled ejection in a predetermined direction.
It finds an advantageous but by no means exclusive application in spacecraft and in particular in satellites, for example for deploying microsatellites from a launch vehicle or a larger satellite. The invention is equally applicable to various terrestrial, maritime (surface and underwater craft) and airborne (aircraft of all kinds) vehicles in which a temporary attachment is to be released at a given time with prompt and accurate movement of the object in question (for example to launch it without external guidance).
Thus applications of the invention include the conduct of scientific experiments in the upper reaches of the terrestrial atmosphere and the exploration of planets in the solar system from an automatic probe. It can be used to eject a storage tank containing a chemical substance to serve as a tracing agent for wind or magnetic field studies, for example. A storage tank of this kind can be ejected from an artificial platform such as a sounding rocket or an interplanetary probe.
2. Description of the Prior Art
Various mechanisms for achieving temporary attachment followed by quick separation and ejection to obtain clean separation between the object and its support are already known.
The following documents may be mentioned in this regard: U.S. Pat. Nos. 4,554,905, 3,887,150, 2,888,294, 3,196,745, 3,597,919, 4,002,120, 4,187,759 and International application WO 82/02527.
In practice these documents propose the use of pressure type energy to bring about unlocking or separation. This energy may be pneumatic, hydraulic or pyrotechnic, for example. In the particularly important case of pyrotechnic energy, the process relies on the pneumatic effects of detonating an explosive.
Pyrotechnic energy is also used in separator devices of the following types: explosive bolts, explosive cutters and pyrotechnic release systems which retract an abutment. They are usually associated with separator pistons.
None of the above-mentioned documents concerns itself significantly with the subsequent movement of the object.
French Patent No. 2,616,856 concerns a mechanism for commanding the separation of a part from a support with which it is initially in contact and with the speed and acceleration of ejection under total control. This patent teaches the interposition of a spring or gas type elastic member between a drive member and the piston in order to apply a clearly defined quantity of energy to the object to be ejected.
French Patent No. 2,661,465 is directed to a device for temporary mechanical attachment and quick separation of an object and a support. This patent teaches that to accurately control the magnitude and direction of the ejection speed the ejector rod should contact the object to be ejected near its center of mass and the receptacle in which the ejector rod slides should be fixed to the object near the opening of a housing provided in the object to provide access to its center of gravity for the ejector rod. Centering areas are provided in the object near the contact area and the opening, respectively.
European Patent No. 0,363,242 concerns a device for temporarily attaching/detaching two members and subsequently separating them. To enable a plurality of attachment and detachment cycles, the device embodies in a hollow body fastened to one member a retaining sleeve adapted to retract radially onto a male member connected to the other member or to move away from the male member to release it. A piston slides in the hollow body and collaborates with a case sliding on the piston and on the sleeve to maneuver the retaining sleeve between its two configurations. An ejector finger is fixed to the inside of the sliding piston by a member adapted to be easily broken. When a pyrotechnic charge is detonated the resulting high pressure operates on the sliding piston and on the case to retract the retaining sleeve and on the ejector finger to apply a thrust to the male member as soon as the member adapted to break easily is broken.
These latter solutions have proved and continue to prove satisfactory.
Nevertheless, in devices of this kind which have a three-fold retain/release/eject function the invention is directed to improved control of the release/ejection sequence to guarantee that release is completed when the ejection thrust is applied. This is to eliminate any unwanted repercussions of the release operation on the quality of ejection.
Strictly speaking, in the device of European Patent No. 0,363,242 the release and ejection operations are not staggered in time as the ejector finger can apply its thrust to the male member before the latter is entirely released or after it is released, depending on the strength of the member adapted to be readily broken and the conditions under which detonation occurs. In the device of French Patent No. 2,661,465 it is the ejection thrust which ruptures the fragile link and therefore brings about release. Finally, in the device of French Patent No. 2,616,856 the elastic member through which the thrust applied to the drive member is transmitted to the ejection piston sometimes achieves a damping of the thrust force and a time offset controlled to a greater or lesser degree and depending in particular on the prestressing (spring device) or pressure (gas device) of the elastic member, which may have diminished in storage because of aging or leaks.
An object of the invention is to provide a device having the three-fold function of temporarily retaining and then releasing and ejecting an object relative to a support in which the thrust phase takes place after the release phase, following a tightly controlled, non-null but possibly very small time interval (in the order of one millisecond compared with the usual time in the order of 8 to 15 seconds), and which is of simple and compact design and easy to operate.